Computer-programs that provide virtual design and drawing tools have wide applicability in both industrial and personal use settings. Some applications provide free-hand sketching capabilities that allow a user to draw lines and objects based on free-hand movement of a contact (e.g., a contact made by a finger or stylus) on a touch-sensitive surface (e.g., a trackpad or touch-screen display). In addition to selecting the color and texture for a drawing tool (e.g., pen, brush, pencil, etc.) used, a user may wish to employ certain conventional drawing aids, such as a straight-edge ruler, a template, a protractor, an angle ruler, etc. It is inconvenient and difficult to use a real-world drawing aid with a virtual drafting environment. Thus, providing virtual drawing aids in computer programs that provide sketching capabilities will improve the functionality of the computer programs. It is challenging to provide virtual drawing aids in a way that are functional, efficient, and ease to use.